U.S. Pat. No. 6,668,770, it is known to configure air path and mixture path approximately the same length. The length of the mixture path should lie between 0.6 times and 1.4 times the length of the air path. In this way, air path and mixture path are to be matched to each other in order to maintain the air/fuel ratio constant, independent of load fluctuations.
The air path includes the length of the transfer channels. Since the mixture path should be approximately as long as the air path, unfavorable spatial conditions result because the mixture path must be configured comparatively long compared to the portion of the air path lying outside of the cylinder. Here, it has been shown that the air/fuel ratio in the combustion chamber is not optimal for the entire operating rpm range for air and mixture channels having approximately the same length.